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AQUATIC COCKEOACHBS. 

 By E. Shelfokd, M.A., F.L.S. 



In 1897 the writer was collecting insects on a mountain close 

 to Kucbing, the capital town of the State of Sarawak, in Borneo, 

 and, whilst examining a small pool at the base of a waterfall for 

 water-beetles, discovered several Cockroaches lurking in the sod- 

 den leaves scattered about the edge of the pool. The insects, 

 when disturbed, took to the water, and dived to the bottom, 

 where they hid under sticks and stones. The habit was suffici- 

 ently remarkable and unexpected to deserve further investigation, 

 and several specimens were captured alive, and placed in a glass 

 tank with some water and an abundance of vegetable debris. All 

 the specimens were immature, and of varying size, ranging from 

 10 millim. to 25 millim. in length. It was observed that they 

 could not endure total immersion in water for any length of 

 time ; if a specimen was confined in a tube full of water, and 

 denied all access to air, it would struggle violently for a few 

 minutes in its efforts to escape, and then sink to the bottom of 

 the tube, and there expire. This is what one might expect from 

 the results of certain experiments conducted by Prof. Plateau, of 

 Ghent, on the relative staying powers of land- and water-insects 

 when totally submerged in water. The distinguished Belgian 

 entomologist found that, whilst terrestrial insects will support 

 an immersion for a period ranging from 97^- hours to 22^ hours, 

 aquatic beetles succumb in periods ranging from 65^ hours to 

 3 hours. The aquatic Cockroach drowns even more rapidly than 

 aquatic beetles, and it was found that a terrestrial Cockroach, 

 though enduring total immersion for a few hours, is unable to 

 remain alive without air for even the minimum time recorded for 

 terrestrial beetles. 



The aquatic Cockroaches that were kept under observation 

 were very inactive, resting for hours at a time on the dead leaves 

 with which they were provided ; generally the front part of the 



